The present invention relates to a process for polymerizing olefin(s) to produce polymers having improved processability. Also, the invention is directed to a bulky ligand metallocene-type catalyst compound and catalyst system for use in the polymerization of olefin(s) to produce polymers that are easier to process into various articles of manufacture. In particular, the invention is directed to cyclic bridged bulky ligand metallocene-type catalyst systems, their use in a polymerization process, and products produced therefrom.
Processability is the ability to economically process and shape a polymer uniformly. Processability involves such elements as how easily the polymer flows, melt strength, and whether or not the extrudate is distortion free. Typical bulky ligand metallocene-type catalyzed polyethylenes (mPE) are somewhat more difficult to process than low density polyethylenes (LDPE) made in a high pressure polymerization process. Generally, mPE""s require more motor power and produce higher extruder pressures to match the extrusion rate of LDPE""s. Typical mPE""s also have lower melt strength which, for example, adversely affects bubble stability during blown film extrusion, and they are prone to melt fracture at commercial shear rates. On the other hand, however, mPE""s exhibit superior physical properties as compared to LDPE""s.
It is now common practice in the industry to add various levels of an LDPE to an mPE to increase melt strength, to increase shear sensitivity, i.e., to increase flow at commercial shear rates; and to reduce the tendency to melt fracture. However, these blends generally have poor mechanical properties as compared with neat mPE.
Traditionally, metallocene catalysts produce polymers having a narrow molecular weight distribution. Narrow molecular weight distribution polymers tend to be more difficult to process. The broader the polymer molecular weight distribution the easier the polymer is to process. A technique to improve the processability of mPE""s is to broaden the products"" molecular weight distribution (MWD) by blending two or more mPE""s with significantly different molecular weights, or by changing to a polymerization catalyst or mixture of catalysts that produce broad MWD polymers.
In the art specific bulky ligand metallocene-type catalyst compound characteristics have been shown to produce polymers that are easier to process. For example, U.S. Pat. No. 5,281,679 discusses bulky ligand metallocene-type catalyst compounds where the bulky ligand is substituted with a substituent having a secondary or tertiary carbon atom for the producing of broader molecular weight distribution polymers. U.S. Pat. No. 5,470,811 describes the use of a mixture of bulky ligand metallocene-type catalysts for producing easy processing polymers. Also, U.S. Pat. No. 5,798,427 addresses the production of polymers having enhanced processability using a bulky ligand metallocene-type catalyst compound where the bulky ligands are specifically substituted indenyl ligands.
A need exists in the industry for a process using a bulky ligand metallocene-type catalyst to produce more easily processable polymers.
This invention relates to a polymerization process utilizing a bridged bulky ligand metallocene-type catalyst system for producing polymer products that have excellent processability and enhanced physical properties. Also, the invention is directed to improved bridged bulky ligand metallocene-type catalyst compounds having a cyclic bridge, catalyst systems comprising these compounds, and polymerizing processes utilizing these compounds.
The preferred polymerization processes are a gas phase or a slurry phase process, most preferably a gas phase process.
In an embodiment, the invention provides for a process for polymerizing ethylene alone or in combination with one or more other olefin(s) in the presence of a cyclic bridged metallocene-type catalyst compound, preferably an achiral cyclic bridged metallocene-type catalyst compound, even more preferably an achiral cyclic bridged metallocene-type catalyst compound having two substituted bulky ligands and an activator. In a most preferred embodiment, the cyclic bridged metallocene-type catalyst compound has two bulky ligands only one of which is a substituted bulky ligand.
In another embodiment, the invention relates to a gas phase or slurry phase process for polymerizing olefin(s) using a cyclic bridged metallocene-type catalyst system to produce a polymer product having a Mz/Mw greater than or equal to 3 and an I21/I2 of greater than 35. In this embodiment, it is particularly preferred that a supported cyclic bridged metallocene-type catalyst system is used.
The invention relates to a polymerization process for producing easy processing polymers using a cyclic bridged bulky ligand metallocene-type catalyst system. It has been suprisingly discovered that using the cyclic bridged metallocene-type catalysts of the invention, particularly in a slurry or gas phase polymerization process, produces polymers that have a high Melt Index Ratio (MIR). MIR is simply the ratio of I21/I2, where I21 is measured by ASTM-D-1238-F and I2 known as Melt Index (MI) is measured by ASTM-D-1238-E.
Generally, bulky ligand metallocene-type catalyst compounds include half and full sandwich compounds having one or more bulky ligands bonded to at least one metal atom. Typical bulky ligand metallocene-type compounds are generally described as containing one or more bulky ligand(s) and one or more leaving group(s) bonded to at least one metal atom. In one preferred embodiment, at least one bulky ligand is xcex7-bonded to a metal atom, most preferably xcex75-bonded to the metal atom.
The bulky ligands are generally represented by one or more open, acyclic, or fused ring(s) or ring system(s) or a combination thereof. These bulky ligands, preferably ring(s) or ring system(s) are typically composed of atoms selected from Groups 13 to 16 atoms of the Periodic Table of Elements, preferably the atoms are selected from the group consisting of carbon, nitrogen, oxygen, silicon, sulfur, phosphorous, boron and aluminum or a combination thereof. Most preferably the ring(s) or ring system(s) are composed of carbon atoms such as but not limited to those cyclopentadienyl ligands or cyclopentadienyl-type ligand structures or other similar functioning ligand structure such as a pentadiene, a cyclooctatetraendiyl or an imide ligand. The metal atom is preferably selected from Groups 3 through 15 and the lanthanide or actinide series of the Periodic Table of Elements. Preferably the metal is a transition metal from Groups 4 through 12, more preferably 4, 5 and 6, and most preferably the metal is from Group 4.
In one embodiment, the bulky ligand metallocene-type catalyst compounds of the invention are represented by the formula:
LALBMQnxe2x80x83xe2x80x83(I)
where M is a metal atom from the Periodic Table of the Elements and may be a Group 3 to 12 metal or from the lanthanide or actinide series of the Periodic Table of Elements, preferably M is a Group 4, 5 or 6 transition metal, more preferably M is a Group 4 transition metal, even more preferably M is zirconium, hafnium or titanium. The bulky ligands, LA and LB, are open, acyclic, or fused ring(s) or ring system(s) such as unsubstituted or substituted, cyclopentadienyl ligands or cyclopentadienyl-type ligands, heteroatom substituted and/or heteroatom containing cyclopentadienyl-type ligands. Non-limiting examples of bulky ligands include cyclopentadienyl ligands, indenyl ligands, benzindenyl ligands, fluorenyl ligands, octahydrofluorenyl ligands, cyclooctatetraendiyl ligands, azenyl ligands, azulene ligands, pentalene ligands, phosphoyl ligands, pyrrolyl ligands, pyrozolyl ligands, carbazolyl ligands, borabenzene ligands and the like, including hydrogenated versions thereof, for example tetrahydroindenyl ligands. In one embodiment, LA and LB may be any other ligand structure capable of xcex7-bonding to M, preferably xcex73-bonding to M, and most preferably xcex75-bonding to M. In another embodiment, LA and LB may comprise one or more heteroatoms, for example, nitrogen, silicon, boron, germanium, sulfur and phosphorous, in combination with carbon atoms to form an open, acyclic, or preferably a fused, ring or ring system, for example, a hetero-cyclopentadienyl ancillary ligand. Other LA and LB bulky ligands include but are not limited to bulky amides, phosphides, alkoxides, aryloxides, imides, carbolides, borollides, porphyrins, phthalocyanines, corrins and other polyazomacrocycles. Independently, each LA and LB may be the same or different type of bulky ligand that is bonded to M.
Independently, each LA and LB may be unsubstituted or substituted with a combination of substituent groups R. Non-limiting examples of substituent groups R include one or more from the group selected from hydrogen, or linear, branched alkyl radicals, or alkenyl radicals, alkynyl radicals, cycloalkyl radicals or aryl radicals, acyl radicals, aroyl radicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- or dialkylcarbamoyl radicals, acyloxy radicals, acylamino radicals, aroylamino radicals, straight, branched or cyclic, alkylene radicals, or combination thereof. Non-limiting examples of alkyl substituents R include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, benzyl or phenyl groups and the like, including all their isomers, for example tertiary butyl, isopropyl, and the like. Other hydrocarbyl radicals include fluoromethyl, fluroethyl, difluroethyl, iodopropyl, bromohexyl, chlorobenzyl and hydrocarbyl substituted organometalloid radicals including trimethylsilyl, trimethylgermyl, methyldiethylsilyl and the like; and halocarbyl-substituted organometalloid radicals including tris(trifluoromethyl)-silyl, methyl-bis(difluoromethyl)silyl, bromomethyldimethylgermyl and the like; and disubstitiuted boron radicals including dimethylboron for example; and disubstituted pnictogen radicals including dimethylamine, dimethylphosphine, diphenylamine, methylphenylphosphine, chalcogen radicals including methoxy, ethoxy, propoxy, phenoxy, methylsulfide and ethylsulfide. Non-hydrogen substituents R include the atoms carbon, silicon, boron, aluminum, nitrogen, phosphorous, oxygen, tin, sulfur, germanium and the like, including olefins such as but not limited to olefinically unsaturated substituents including vinyl-terminated ligands, for example but-3-enyl, prop-2-enyl, hex-5-enyl and the like. Also, at least two R groups, preferably two adjacent R groups, are joined to form a ring structure having from 3 to 30 atoms selected from carbon, nitrogen, oxygen, phosphorous, silicon, germanium, aluminum, boron or a combination thereof. Also, a substituent group R group such as 1-butanyl may form a carbon sigma bond to the metal M.
Other ligands may be bonded to the metal M, such as at least one leaving group Q. For the purposes of this patent specification and appended claims the term xe2x80x9cleaving groupxe2x80x9d is any ligand that can be abstracted from a bulky ligand metallocene-type catalyst compound to form a bulky ligand metallocene-type catalyst cation capable of polymerizing one or more olefin(s). In one embodiment, Q is a monoanionic labile ligand having a sigma-bond to M. Depending on the oxidation state of the metal, the value for n is 0, 1 or 2 such that formula (I) above represents a neutral bulky ligand metallocene-type catalyst compound. Non-limiting examples of Q ligands include weak bases such as amines, phosphines, ethers, carboxylates, dienes, hydrocarbyl radicals having from 1 to 20 carbon atoms, hydrides or halogens and the like or a combination thereof. In another embodiment, two or more Q""s form a part of a fused ring or ring system. Other examples of Q ligands include those substituents for R as described above and including cyclobutyl, cyclohexyl, heptyl, tolyl, trifluromethyl, tetramethylene, pentamethylene, methylidene, methyoxy, ethyoxy, propoxy, phenoxy, bis(N-methylanilide), dimethylamide, dimethylphosphide radicals and the like.
The bridged bulky ligand metallocene-type catalyst compounds of the invention include those of formula (I) where LA and LB are bridged to each other by a cyclic bridging group, A. For the purposes of this patent application and appended claims, the cyclic bridging group A comprises greater than 3 non-hydrogen atoms, preferably greater than 3 carbon atoms forming a ring or ring system about at least one other Group 13 to 16 atom. Non-limiting examples of Group 13 to 16 atoms include at least one of a carbon, oxygen, nitrogen, silicon, boron, germanium and tin atom or a combination thereof. In a preferred embodiment, the cyclic bridging group A contains a carbon, silicon or germanium atom, most preferably A contains at least one silicon atom. The atoms forming the ring system of A may be substituted with substituents as defined above for R.
Non-limiting examples of cyclic bridging groups A include cyclo-tri or tetra-alkylene silyl or include cyclo-tri or tetra-alkylene germyl groups, for example, cyclotrimethylenesilyl group or cyclotetramethylenesilyl group.
Other examples of cyclic bridging groups are represented by the following structures: 
In a preferred embodiment, the bulky ligand metallocene-type catalyst compounds of the invention include cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl)zirconium dichloride, cyclotetramethylenesilyl(tetramethyl cyclopentadienyl)(cyclopentadienyl)zirconium dichloride, cyclotrimethylenesilyl (tetramethyl cyclopentadienyl)(2-methyl indenyl)zirconium dichloride, cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(3-methyl cyclopentadienyl)zirconium dichloride, cyclotrimethylenesilyl bis(2-methyl indenyl)zirconium dichloride, cyclotrimethylenesilyl(tetramethyl cyclopentadienyl)(2,3,5-trimethyl cyclopentadienyl) zirconium dichloride, and cyclotrimethylenesilyl bis(tetra methyl cyclopentadienyl) zirconium dichloride.
In another embodiment, the bulky ligand metallocene-type catalyst compound of the invention is represented by the formula:
(C5H4xe2x88x92dRd)(Rxe2x80x2AxRxe2x80x2)(C5H4xe2x88x92dRd)M Qgxe2x88x922xe2x80x83xe2x80x83(II)
where M is a Group 4, 5, 6 transition metal, (C5H4xe2x88x92dRd) is an unsubstituted or substituted, cyclopentadienyl ligand or cyclopentadienyl-type bulky ligand bonded to M, each R, which can be the same or different, is hydrogen or a substituent group containing up to 50 non-hydrogen atoms or substituted or unsubstituted hydrocarbyl having from 1 to 30 carbon atoms or combinations thereof, or two or more carbon atoms are joined together to form a part of a substituted or unsubstituted ring or ring system having 4 to 30 carbon atoms, Rxe2x80x2AxRxe2x80x2 is a cyclic bridging group, where A is one or more of, or a combination of carbon, germanium, silicon, tin, phosphorous or bridging two (C5H4xe2x88x92dRd) rings, and the two Rxe2x80x2""s form a cyclic ring or ring system with A; more particularly, non-limiting examples of cyclic bridging group A may be represented by Rxe2x80x22C, Rxe2x80x22Si, Rxe2x80x22Ge and Rxe2x80x2P, where the two Rxe2x80x2""s are joined to form a ring or ring system. In one embodiment, Rxe2x80x2 is a hydrocarbyl containing a heteroatom, for example boron, nitrogen, oxygen or a combination thereof The two Rxe2x80x2""s may be independently, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, hydrocarbyl-substituted organometalloid, halocarbyl-substituted organometalloid, where the two Rxe2x80x2""s may be joined to form a ring or ring system having from 2 to 100 non-hydrogen atoms, preferably from 3 to 50 carbon atoms; and independently, each Q can be the same or different is a hydride, substituted or unsubstituted, linear, cyclic or branched, hydrocarbyl having from 1 to 30 carbon atoms, halogen, alkoxides, aryloxides, amides, phosphides, or any other univalent anionic ligand or combination thereof, also, two Q""s together may form an alkylidene ligand or cyclometallated hydrocarbyl ligand or other divalent anionic chelating ligand, where g is an integer corresponding to the formal oxidation state of M, and d is an integer selected from 0, 1, 2, 3 or 4 and denoting the degree of substitution, x is an integer from 1 to 4.
In one embodiment, the cyclic bridged bulky ligand metallocene-type catalyst compounds are those where the R substituents on the bulky ligands LA, LB, (C5H4xe2x88x92dRd) of formulas (I) and (II) are substituted with the same or different number of substituents on each of the bulky ligands. In another embodiment, the bulky ligands LA, LB, (C5H4xe2x88x92dRd) of formulas (I) and (II) are different from each other.
In a preferred embodiment, the bulky ligands of the metallocene-type catalyst compounds of formula (I) and (II) are asymmetrically substituted. In another preferred embodiment, at least one of the bulky ligands LA, LB, (C5H4xe2x88x92dRd) of formulas (I) and (II) is unsubstituted.
In the most preferred embodiment, the cyclic bridged metallocene-type catalyst compounds of the invention are achiral.
Other bulky ligand metallocene-type catalysts compounds useful in the invention include cyclic bridged heteroatom, mono-bulky ligand metallocene-type compounds. These types of catalysts and catalyst systems are described in, for example, PCT publication WO 92/00333, WO 94/07928, WO 91/04257, WO 94/03506, W096/00244 and WO 97/15602 and U.S. Pat. Nos. 5,057,475, 5,096,867, 5,055,438, 5,198,401, 5,227,440 and 5,264,405 and European publication EP-A-0 420 436, all of which are herein fully incorporated by reference. Other bulky ligand metallocene-type catalyst compounds and catalyst systems useful in the invention may include those described in U.S. Pat. Nos. 5,064,802, 5,145,819, 5,149,819, 5,243,001, 5,239,022, 5,276,208, 5,296,434, 5,321,106, 5,329,031, 5,304,614, 5,677,401, 5,723,398 and 5,753,578 and PCT publications WO 93/08221, WO 93/08199, WO 95/07140, WO 98/11144 and European publications EP-A-0 578 838, EP-A-0 638 595, EP-B-0 513 380, EP-A1-0 816 372, EP-A2-0 839 834 and EP-B1-0 632 819, all of which are herein fully incorporated by reference.
In another embodiment, the cyclic bridged bulky ligand metallocene-type catalyst compound is represented by the formula:
LCAJMQnxe2x80x83xe2x80x83(III)
where M is a Group 3 to 10 metal atom or a metal selected from the Group of actinides and lanthanides of the Periodic Table of Elements, preferably M is a Group 4 to 10 transition metal, and more preferably M is a Group 4, 5 or 6 transition metal, and most preferably M is a Group 4 transition metal in any oxidation state, especially titanium; LC is a substituted or unsubstituted bulky ligand bonded to M; J is bonded to M; A is bonded to L and J; J is a heteroatom ancillary ligand; and A is a cyclic bridging group; Q is a univalent anionic ligand; and n is the integer 0,1 or 2. In formula (III) above, LC, A and J form a fused ring system. In an embodiment, LC of formula (III) is as defined above for LA in formula (I), and A, M and Q of formula (III) are as defined above in formula (I).
In another embodiment of this invention the bulky ligand metallocene-type catalyst compound useful in the invention is represented by the formula:
xe2x80x83(C5H5xe2x88x92yxe2x88x92xRx)(Rxe2x80x3AyRxe2x80x3)(JRxe2x80x2zxe2x88x921xe2x88x92y)M(Q)n(Lxe2x80x2)wxe2x80x83xe2x80x83(IV)
where M is a transition metal from Group 4 in any oxidation state, preferably, titanium, zirconium or hafnium, most preferably titanium in either a +2, +3 or +4 oxidation state. A combination of compounds represented by formula (IV) with the transition metal in different oxidation states is also contemplated. LC is represented by (C5H5xe2x88x92yxe2x88x92xRx) and is a bulky ligand as described above. For purposes of formula (IV) R0 means no substituent. More particularly (C5H5xe2x88x92yxe2x88x92xRx) is a cyclopentadienyl ring or cyclopentadienyl-type ring or ring system which is substituted with from 0 to 4 substituent groups R, and xe2x80x9cxxe2x80x9d is 0, 1, 2, 3 or 4 denoting the degree of substitution. Each R is, independently, a radical selected from a group consisting of 1 to 30 non-hydrogen atoms. More particularly, R is a hydrocarbyl radical or a substituted hydrocarbyl radical having from 1 to 30 carbon atoms, or a hydrocarbyl-substituted metalloid radical where the metalloid is a Group 14 or 15 element, preferably silicon or nitrogen or a combination thereof, and halogen radicals and mixtures thereof. Substituent R groups also include silyl, germyl, amine, and hydrocarbyloxy groups and mixtures thereof. Also, in another embodiment, (C5H5xe2x88x92yxe2x88x92xRx) is a cyclopentadienyl ligand in which two R groups, preferably two adjacent R groups are joined to form a ring or ring system having from 3 to 50 atoms, preferably from 3 to 30 carbon atoms. This ring system may form a saturated or unsaturated polycyclic cyclopentadienyl-type ligand such as those bulky ligands described above, for example, indenyl, tetrahydroindenyl, fluorenyl or octahydrofluorenyl.
The (JRxe2x80x2zxe2x88x921xe2x88x92y) of formula (IV) is a heteroatom containing ligand in which J is an element with a coordination number of three from Group 15 or an element with a coordination number of two from Group 16 of the Periodic Table of Elements. Preferably J is a nitrogen, phosphorus, oxygen or sulfur atom with nitrogen being most preferred. Each Rxe2x80x2 is, independently, a radical selected from the group consisting of hydrocarbyl radicals having from 1 to 20 carbon atoms, or as defined for R in formula (I) above; the xe2x80x9cyxe2x80x9d is 1 to 4, preferably 1 to 2, most preferably y is 1, and the xe2x80x9czxe2x80x9d is the coordination number of the element J. In one embodiment, in formula (IV), the J of formula (III) is represented by (JRxe2x80x2zxe2x88x921xe2x88x92y).
In formula (IV) each Q is, independently, any univalent anionic ligand such as halogen, hydride, or substituted or unsubstituted hydrocarbyl having from 1 to 30 carbon atoms, alkoxide, aryloxide, sulfide, silyl, amide or phosphide. Q may also include hydrocarbyl groups having ethylenic unsaturation thereby forming a xcex73 bond to M. Also, two Q""s may be an alkylidene, a cyclometallated hydrocarbyl or any other divalent anionic chelating ligand. The integer n may be 0, 1, 2 or 3.
The (Rxe2x80x3AyRxe2x80x3) of formula (IV) is a cyclic bridging group where A is a Group 13 to 16 element, preferably a Group 14 and 15 element, most preferably a Group 14 element. Non-limiting examples of A include one or more of, or a combination of carbon, silicon, germanium, boron, nitrogen, phosphorous, preferably at least one silicon atom. The two Rxe2x80x3""s for a ring or ring system about A, the two Rxe2x80x2""s together having from 3 to 100 non-hydrogen atoms, preferably from 3 to 50 carbon atom.
Optionally associated with formula (IV) is Lxe2x80x2, a Lewis base such as diethylether, tetraethylammonium chloride, tetrahydrofuran, dimethylaniline, aniline, trimethylphosphine, n-butylamine, and the like; and w is a number from 0 to 3. Additionally, Lxe2x80x2 may be bonded to any of R, Rxe2x80x2 or Q and n is 0, 1, 2 or 3.
Activator and Activation Methods for the Bulky Ligand Metallocene-Type Catalyst Compounds
The above described cyclic bridged bulky ligand metallocene-type catalyst compounds are typically activated in various ways to yield catalyst compounds having a vacant coordination site that will coordinate, insert, and polymerize olefin(s).
For the purposes of this patent specification and appended claims, the term xe2x80x9cactivatorxe2x80x9d is defined to be any compound or component or method which can activate any of the bulky ligand metallocene-type catalyst compounds of the invention as described above. Non-limiting activators, for example may include a Lewis acid or a non-coordinating ionic activator or ionizing activator or any other compound including Lewis bases, aluminum alkyls, conventional-type cocatalysts and combinations thereof that can convert a neutral bulky ligand metallocene-type catalyst compound to a catalytically active bulky ligand metallocene cation. It is within the scope of this invention to use alumoxane or modified alumoxane as an activator, and/or to also use ionizing activators, neutral or ionic, such as tri (n-butyl)ammonium tetrakis(pentafluorophenyl)boron or a trisperfluorophenyl boron metalloid precursor or a trisperfluoronaphtyl boron metalloid precursor that would ionize the neutral bulky ligand metallocene-type catalyst compound.
In one embodiment, an activation method using ionizing ionic compounds not containing an active proton but capable of producing both a bulky ligand metallocene-type catalyst cation and a non-coordinating anion are also contemplated, and are described in EP-A-0 426 637, EP-A- 0 573 403 and U.S. Pat. No. 5,387,568, which are all herein incorporated by reference.
There are a variety of methods for preparing alumoxane and modified alumoxanes, non-limiting examples of which are described in U.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031, 5,391,793, 5,391,529, 5,693,838, 5,731,253, 5,731,451 5,744,656 and European publications EP-A-0 561 476, EP-B1-0 279 586 and EP-A-0 594-218, and PCT publication WO 94/10180, all of which are herein fully incorporated by reference.
Ionizing compounds may contain an active proton, or some other cation associated with but not coordinated to or only loosely coordinated to the remaining ion of the ionizing compound. Such compounds and the like are described in European publications EP-A-0 570 982, EP-A-0 520 732, EP-A-0 495 375, EP-A-500 944, EP-A-0 277 003 and EP-A-0 277 004, and U.S. Pat. Nos. 5,153,157, 5,198,401, 5,066,741, 5,206,197, 5,241,025, 5,384,299 and 5,502,124 and U.S. patent application Ser. No. 08/285,380, filed Aug. 3, 1994, all of which are herein fully incorporated by reference.
Other activators include those described in PCT publication WO 98/07515 such as tris (2, 2xe2x80x2, 2xe2x80x3-nonafluorobiphenyl)fluoroaluminate, which publication is fully incorporated herein by reference. Combinations of activators are also contemplated by the invention, for example, alumoxanes and ionizing activators in combinations, see for example, PCT publications WO 94/07928 and WO 95/14044 and U.S. Pat. Nos. 5,153,157 and 5,453,410 all of which are herein fully incorporated by reference. WO 98/09996 incorporated herein by reference describes activating bulky ligand metallocene-type catalyst compounds with perchlorates, periodates and iodates including their hydrates. WO 98/30602 and WO 98/30603 incorporated by reference describe the use of lithium (2,2xe2x80x2-bisphenyl-ditrimethylsilicate). 4THF as an activator for a bulky ligand metallocene-type catalyst compound. Also, methods of activation such as using radiation (see EP-B1-0 615 981 herein incorporated by reference), electro-chemical oxidation, and the like are also contemplated as activating methods for the purposes of rendering the neutral bulky ligand metallocene-type catalyst compound or precursor to a bulky ligand metallocene-type cation capable of polymerizing olefins.
It is further contemplated by the invention that other catalysts can be combined with the cyclic bridged bulky ligand metallocene-type catalyst compounds of the invention. For example, see U.S. Pat. Nos. 4,937,299, 4,935,474, 5,281,679, 5,359,015, 5,470,811, and 5,719,241 all of which are herein fully incorporated herein reference.
In another embodiment of the invention one or more bulky ligand metallocene-type catalyst compounds or catalyst systems may be used in combination with one or more conventional-type catalyst compounds or catalyst systems. Non-limiting examples of mixed catalysts and catalyst systems are described in U.S. Pat. Nos. 4,159,965, 4,325,837, 4,701,432, 5,124,418, 5,077,255, 5,183,867, 5,391,660, 5,395,810, 5,691,264, 5,723,399 and 5,767,031 and PCT Publication WO 96/23010 published Aug. 1, 1996, all of which are herein fully incorporated by reference.
The above described cyclic bulky ligand metallocene-type catalyst compounds and catalyst systems may be combined with one or more support materials or carriers using one of the support methods well known in the art or as described below. In the preferred embodiment, the method of the invention uses a polymerization catalyst in a supported form. For example, in a most preferred embodiment, a bulky ligand metallocene-type catalyst compound or catalyst system is in a supported form, for example deposited on, bonded to, contacted with, or incorporated within, adsorbed or absorbed in, or on, a support or carrier.
The terms xe2x80x9csupportxe2x80x9d or xe2x80x9ccarrierxe2x80x9d are used interchangeably and are any support material, preferably a porous support material, for example, talc, inorganic oxides and inorganic chlorides. Other carriers include resinous support materials such as polystyrene, functionalized or crosslinked organic supports, such as polystyrene divinyl benzene polyolefins or polymeric compounds, zeolites, clays, or any other organic or inorganic support material and the like, or mixtures thereof.
The preferred carriers are inorganic oxides that include those Group 2, 3, 4, 5, 13 or 14 metal oxides. The preferred supports include silica, alumina, silica-alumina, magnesium chloride, and mixtures thereof. Other useful supports include magnesia, titania, zirconia, montmorillonite (EP-B1 0 511 665) and the like. Also, combinations of these support materials may be used, for example, silica-chromium, silica-alumina, silica-titania and the like.
It is preferred that the carrier, most preferably an inorganic oxide, has a surface area in the range of from about 10 to about 700 m2/g, pore volume in the range of from about 0.1 to about 4.0 cc/g and average particle size in the range of from about 5 to about 500 sum. More preferably, the surface area of the carrier is in the range of from about 50 to about 500 m2/g, pore volume of from about 0.5 to about 3.5 cc/g and average particle size of from about 10 to about 200 xcexcm. Most preferably the surface area of the carrier is in the range is from about 100 to about 400 m2/g, pore volume from about 0.8 to about 3.0 cc/g and average particle size is from about 5 to about 100 xcexcm. The average pore size of the carrier of the invention typically has pore size in the range of from 10 to 1000 xc3x85, preferably 50 to about 500 xc3x85, and most preferably 75 to about 350 xc3x85.
Examples of supporting the bulky ligand metallocene-type catalyst systems of the invention are described in U.S. Pat. Nos. 4,701,432, 4,808,561, 4,912,075, 4,925,821, 4,937,217, 5,008,228, 5,238,892, 5,240,894, 5,332,706, 5,346,925, 5,422,325, 5,466,649, 5,466,766, 5,468,702, 5,529,965, 5,554,704, 5,629,253, 5,639,835, 5,625,015, 5,643,847, 5,665,665, 5,698,487, 5,714,424, 5,723,400, 5,723,402, 5,731,261, 5,759,940, 5,767,032 and 5,770,664 and U.S. application Ser. No. 271,598 filed Jul. 7, 1994 and Ser. No. 788,736 filed Jan. 23, 1997 and PCT publications WO 95/32995, WO 95/14044, WO 96/06187 and WO 97/02297 all of which are herein fully incorporated by reference.
In one embodiment, the cyclic bridged bulky ligand metallocene-type catalyst compounds of the invention may be deposited on the same or separate supports together with an activator, or the activator may be used in an unsupported form, or may be deposited on a support different from the supported bulky ligand metallocene-type catalyst compounds of the invention, or any combination thereof.
There are various other methods in the art for supporting a polymerization catalyst compound or catalyst system of the invention. For example, the cyclic bridged bulky ligand metallocene-type catalyst compound of the invention may contain a polymer bound ligand as described in U.S. Pat. Nos. 5,473,202 and 5,770,755, which is herein fully incorporated by reference; the bulky ligand metallocene-type catalyst system of the invention may be spray dried as described in U.S. Pat. No. 5,648,310, which is herein fully incorporated by reference; the support used with the cyclic bridged bulky ligand metallocene-type catalyst system of the invention is functionalized as described in European publication EP-A-0 802 203, which is herein fully incorporated by reference, or at least one substituent or leaving group is selected as described in U.S. Pat. No. 5,688,880, which is herein fully incorporated by reference.
In a preferred embodiment, the invention provides for a supported cyclic bridged bulky ligand metallocene-type catalyst system that includes an antistatic agent or surface modifier that is used in the preparation of the supported catalyst system as described in PCT publication WO 96/11960, which is herein fully incorporated by reference. The catalyst systems of the invention can be prepared in the presence of an olefin, for example hexene-1.
A preferred method for producing the supported cyclic bridged bulky ligand metallocene-type catalyst system of the invention is described below and is described in U.S. application Ser. No. 265,533, filed Jun. 24, 1994 and Ser. No. 265,532, filed Jun. 24, 1994 and PCT publications WO 96/00245 and WO 96/00243 both published Jan. 4, 1996, all of which are herein fully incorporated by reference. In this preferred method, the cyclic bridged bulky ligand metallocene-type catalyst compound is slurried in a liquid to form a metallocene solution and a separate solution is formed containing an activator and a liquid. The liquid may be any compatible solvent or other liquid capable of forming a solution or the like with the cyclic bridged bulky ligand metallocene-type catalyst compounds and/or activator of the invention. In the most preferred embodiment the liquid is a cyclic aliphatic or aromatic hydrocarbon, most preferably toluene. The cyclic bridged bulky ligand metallocene-type catalyst compound and activator solutions are mixed together and added to a porous support or the porous support is added to the solutions such that the total volume of the bulky ligand metallocene-type catalyst compound solution and the activator solution or the bulky ligand metallocene-type catalyst compound and activator solution is less than four times the pore volume of the porous support, more preferably less than three times, even more preferably less than two times; preferred ranges being from 1.1 times to 3.5 times range and most preferably in the 1.2 to 3 times range.
Procedures for measuring the total pore volume of a porous support are well known in the art. Details of one of these procedures is discussed in Volume 1, Experimental Methods in Catalytic Research (Academic Press, 1968) (specifically see pages 67-96). This preferred procedure involves the use of a classical BET apparatus for nitrogen absorption. Another method well known in the art is described in Innes, Total Porosity and Particle Density of Fluid Catalysts By Liquid Titration, Vol. 28, No. 3, Analytical Chemistry 332-334 (March, 1956).
The mole ratio of the metal of the activator component to the metal of the supported cyclic bridged bulky ligand metallocene-type catalyst compounds are in the range of between 0.3:1 to 1000:1, preferably 20:1 to 800:1, and most preferably 50:1 to 500:1. Where the activator is an ionizing activator such as those based on the anion tetrakis(pentafluorophenyl)boron, the mole ratio of the metal of the activator component to the metal component of the cyclic bridged bulky ligand metallocene-type catalyst is preferably in the range of between 0.3:1 to 3:1. Where an unsupported cyclic bridged bulky ligand metallocene-type catalyst system is utilized, the mole ratio of the metal of the activator component to the metal of the cyclic bridged bulky ligand metallocene-type catalyst compound is in the range of between 0.3:1 to 10,000:1, preferably 100:1 to 5000:1, and most preferably 500:1 to 2000:1.
In one embodiment of the invention, olefin(s), preferably C2 to C30 olefin(s) or alpha-olefin(s), preferably ethylene or propylene or combinations thereof are prepolymerized in the presence of the cyclic bridged bulky ligand metallocene-type catalyst system of the invention prior to the main polymerization. The prepolymerization can be carried out batchwise or continuously in gas, solution or slurry phase including at elevated pressures. The prepolymerization can take place with any olefin monomer or combination and/or in the presence of any molecular weight controlling agent such as hydrogen. For examples of prepolymerization procedures, see U.S. Pat. Nos. 4,748,221, 4,789,359, 4,923,833, 4,921,825, 5,283,278 and 5,705,578 and European publication EP-B-0279 863 and PCT Publication WO 97/44371 all of which are herein fully incorporated by reference.
In one embodiment the polymerization catalyst is used in an unsupported form, preferably in a liquid form such as described in U.S. Pat. Nos. 5,317,036 and 5,693,727 and European publication EP-A-0 593 083, all of which are herein incorporated by reference. The polymerization catalyst in liquid form can be fed to a reactor as described in PCT publication WO 97/46599, which is fully incorporated herein by reference.
In one embodiment, the cyclic bridged metallocene-type catalysts of the invention can be combined with a carboxylic acid salt of a metal ester, for example aluminum carboxylates such as aluminum mono, di- and tri- stearates, aluminum octoates, oleates and cyclohexylbutyrates, as described in U.S. application Ser. No. 09/113,216, filed Jul. 10, 1998.
The catalysts and catalyst systems of the invention described above are suitable for use in any polymerization process over a wide range of temperatures and pressures. The temperatures may be in the range of from xe2x88x9260xc2x0 C. to about 280xc2x0 C., preferably from 50xc2x0 C. to about 200xc2x0 C., and the pressures employed may be in the range from 1 atmosphere to about 500 atmospheres or higher.
Polymerization processes include solution, gas phase, slurry phase and a high pressure process or a combination thereof. Particularly preferred is a gas phase or slurry phase polymerization of one or more olefins at least one of which is ethylene or propylene.
In one embodiment, the process of this invention is directed toward a solution, high pressure, slurry or gas phase polymerization process of one or more olefin monomers having from 2 to 30 carbon atoms, preferably 2 to 12 carbon atoms, and more preferably 2 to 8 carbon atoms. The invention is particularly well suited to the polymerization of two or more olefin monomers of ethylene, propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene- 1 and decene-1.
Other monomers useful in the process of the invention include ethylenically unsaturated monomers, diolefins having 4 to 18 carbon atoms, conjugated or nonconjugated dienes, polyenes, vinyl monomers and cyclic olefins. Non-limiting monomers useful in the invention may include norbornene, norbornadiene, isobutylene, isoprene, vinylbenzocyclobutane, styrenes, alkyl substituted styrene, ethylidene norbornene, dicyclopentadiene and cyclopentene.
In the most preferred embodiment of the process of the invention, a copolymer of ethylene is produced, where with ethylene, a comonomer having at least one alpha-olefin having from 4 to 15 carbon atoms, preferably from 4 to 12 carbon atoms, and most preferably from 4 to 8 carbon atoms, is polymerized in a gas phase process.
In another embodiment of the process of the invention, ethylene or propylene is polymerized with at least two different comonomers, optionally one of which may be a diene, to form a terpolymer.
In one embodiment, the invention is directed to a polymerization process, particularly a gas phase or slurry phase process, for polymerizing propylene alone or with one or more other monomers including ethylene, and/or other olefins having from 4 to 12 carbon atoms. Polypropylene polymers may be produced using the particularly bridged bulky ligand metallocene-type catalysts as described in U.S. Pat. Nos. 5,296,434 and 5,278,264, both of which are herein incorporated by reference.
Typically in a gas phase polymerization process a continuous cycle is employed where in one part of the cycle of a reactor system, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed from the recycle composition in another part of the cycle by a cooling system external to the reactor. Generally, in a gas fluidized bed process for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670, 5,317,036, 5,352,749, 5,405,922, 5,436,304, 5,453,471, 5,462,999, 5,616,661 and 5,668,228, all of which are fully incorporated herein by reference.)
The reactor pressure in a gas phase process may vary from about 100 psig (690 kPa) to about 500 psig (3448 kPa), preferably in the range of from about 200 psig (1379 kPa) to about 400 psig (2759 kPa), more preferably in the range of from about 250 psig (1724 kPa) to about 350 psig (2414 kPa).
The reactor temperature in a gas phase process may vary from about 30xc2x0 C. to about 120xc2x0 C., preferably from about 60xc2x0 C. to about 115xc2x0 C., more preferably in the range of from about 70xc2x0 C. to 110xc2x0 C., and most preferably in the range of from about 70xc2x0 C. to about 95xc2x0 C.
Other gas phase processes contemplated by the process of the invention include those described in U.S. Pat. Nos. 5,627,242, 5,665,818 and 5,677,375, and European publications EP-A-0 794 200, EP-A-0 802 202 and EP-B-634 421 all of which are herein fully incorporated by reference.
In a preferred embodiment, the reactor utilized in the present invention is capable and the process of the invention is producing greater than 500 lbs of polymer per hour (227 Kg/hr) to about 200,000 lbs/hr (90,900 Kg/hr) or higher of polymer, preferably greater than 1000 lbs/hr (455 Kg/hr), more preferably greater than 10,000 lbs/hr (4540 Kg/hr), even more preferably greater than 25,000 lbs/hr (11,300 Kg/hr), still more preferably greater than 35,000 lbs/hr (15,900 Kg/hr), still even more preferably greater than 50,000 lbs/hr (22,700 Kg/hr) and most preferably greater than 65,000 lbs/hr (29,000 Kg/hr) to greater than 100,000 lbs/hr (45,500 Kg/hr).
A slurry polymerization process generally uses pressures in the range of from about 1 to about 50 atmospheres and even greater and temperatures in the range of 0xc2x0 C. to about 120xc2x0 C. In a slurry polymerization, a suspension of solid, particulate polymer is formed in a liquid polymerization diluent medium to which ethylene and comonomers and often hydrogen along with catalyst are added. The suspension including diluent is intermittently or continuously removed from the reactor where the volatile components are separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquid diluent employed in the polymerization medium is typically an alkane having from 3 to 7 carbon atoms, preferably a branched alkane. The medium employed should be liquid under the conditions of polymerization and relatively inert. When a propane medium is used the process must be operated above the reaction diluent critical temperature and pressure. Preferably, a hexane or an isobutane medium is employed.
A preferred polymerization technique of the invention is referred to as a particle form polymerization, or a slurry process where the temperature is kept below the temperature at which the polymer goes into solution. Such technique is well known in the art, and described in for instance U.S. Pat. No. 3,248,179 which is fully incorporated herein by reference. Other slurry processes include those employing a loop reactor and those utilizing a plurality of stirred reactors in series, parallel, or combinations thereof. Non-limiting examples of slurry processes include continuous loop or stirred tank processes. Also, other examples of slurry processes are described in U.S. Pat. No. 4,613,484, which is herein fully incorporated by reference.
In an embodiment the reactor used in the slurry process of the invention is capable of and the process of the invention is producing greater than 2000 lbs of polymer per hour (907 Kg/hr), more preferably greater than 5000 lbs/hr (2268 Kg/hr), and most preferably greater than 10,000 lbs/hr (4540 Kg/hr). In another embodiment the slurry reactor used in the process of the invention is producing greater than 15,000 lbs of polymer per hour (6804 Kg/hr), preferably greater than 25,000 lbs/hr (11,340 Kg/hr) to about 100,000 lbs/hr (45,500 Kg/hr).
Examples of solution processes are described in U.S. Pat. Nos. 4,271,060, 5,001,205, 5,236,998 and 5,589,555, which are fully incorporated herein by reference.
A preferred process of the invention is where the process, preferably a slurry or gas phase process is operated in the presence of a bulky ligand metallocene-type catalyst system of the invention and in the absence of or essentially free of any scavengers, such as triethylaluminum, trimethylaluminum, tri-isobutylaluminum and tri-n-hexylaluminum and diethyl aluminum chloride, dibutyl zinc and the like. This preferred process is described in PCT publication WO 96/08520 and U.S. Pat. No. 5,712,352 and 5,763,543, which are herein fully incorporated by reference. In another preferred embodiment of the process of the invention, the process is operated by introducing a benzyl compound into the reactor and/or contacting a benzil compound with the bulky ligand metallocene-type catalyst system of the invention prior to its introduction into the reactor.
The polymers produced by the process of the invention can be used in a wide variety of products and end-use applications. The polymers produced by the process of the invention include linear low density polyethylene, elastomers, plastomers, high density polyethylenes, low density polyethylenes, polypropylene and polypropylene copolymers.
The polymers, typically ethylene based polymers, have a density in the range of from 0.86 g/cc to 0.97 g/cc, preferably in the range of from 0.88 g/cc to 0.965 g/cc, more preferably in the range of from 0.900 g/cc to 0.96 g/cc, even more preferably in the range of from 0.905 g/cc to 0.95 g/cc, yet even more preferably in the range from 0.910 g/cc to 0.940 g/cc, and most preferably greater than 0.915 g/cc to about 0.930 g/cc.
The melt strength of the polymers produced using the catalyst of the invention are greater than 4 cN, preferably greater than 5 cN. For purposes of this patent application and appended claims melt strength is measured with an Instron capillary rheometer in conjunction with the Goettfert Rheotens melt strength apparatus. A polymer melt strand extruded from the capillary die is gripped between two counter-rotating wheels on the apparatus. The take-up speed is increased at a constant acceleration of 24 mm/sec2, which is controlled by the Acceleration Programmer (Model 45917, at a setting of 12). The maximum pulling force (in the unit of cN) achieved before the strand breaks or starts to show draw-resonance is determined as the melt strength. The temperature of the rheometer is set at 190xc2x0 C. The capillary die has a length of one inch (2.54 cm) and a diameter of 0.06xe2x80x2 (0.1 5cm). The polymer melt is extruded from the die at a speed of 3 inch/min (7.62 cm/min). The distance between the die exit and the wheel contact point should be 3.94 inches (100 mm).
The polymers produced by the process of the invention typically have a molecular weight distribution, a weight average molecular weight to number average molecular weight (Mw/Mn) of greater than 1.5 to about 15, particularly greater than 2 to about 10, more preferably greater than about 2.5 to less than about 8, and most preferably from 3.0 to 8.
In one preferred embodiment, the polymers of the present invention have a Mz/Mw of greater than or equal to 3, preferably greater than 3. Mz is the z-average molecular weight. In another preferred embodiment, the polymers of the invention have a Mz/Mw of greater than or equal to 3.0 to about 4. In yet another preferred embodiment, the Mz/Mw is in the range greater than 3 to less than 4.
Also, the polymers of the invention typically have a narrow composition distribution as measured by Composition Distribution Breadth Index (CDBI). Further details of determining the CDBI of a copolymer are known to those skilled in the art. See, for example, PCT Patent Application WO 93/03093, published Feb. 18, 1993, which is fully incorporated herein by reference.
The bulky ligand metallocene-type catalyzed polymers of the invention in one embodiment have CDBI""s generally in the range of greater than 50% to 100%, preferably 99%, preferably in the range of 55% to 85%, and more preferably 60% to 80%, even more preferably greater than 60%, still even more preferably greater than 65%. In another embodiment, polymers produced using a bulky ligand metallocene-type catalyst system of the invention have a CDBI less than 50%, more preferably less than 40%, and most preferably less than 30%.
The polymers of the present invention in one embodiment have a melt index (MI) or (I2) as measured by ASTM-D-1238-E in the range from 0.01 dg/min to 1000 dg/min, more preferably from about 0.01 dg/min to about 100 dg/min, even more preferably from about 0.1 dg/min to about 50 dg/min, and most preferably from about 0.1 dg/min to about 10 dg/min.
The polymers of the invention in an embodiment have a melt index ratio (I21/I2) (I21 is measured by ASTM-D-1238-F) of from 30 to less than 200, more preferably from about 35 to less than 100, and most preferably from 40 to 95.
The polymers of the invention in a preferred embodiment have a melt index ratio (I21/I2) (I2 is measured by ASTM-D-1238-F) of from preferably greater than 30, more preferably greater than 35, even more preferably greater that 40, still even more preferably greater than 50 and most preferably greater than 65.
The polymers of the invention may be blended and/or coextruded with any other polymer. Non-limiting examples of other polymers include linear low density polyethylenes produced via conventional Ziegler-Natta and/or bulky ligand metallocene-type catalysis, elastomers, plastomers, high pressure low density polyethylene, high density polyethylenes, polypropylenes and the like.
Polymers produced by the process of the invention and blends thereof are useful in such forming operations as film, sheet, and fiber extrusion and co-extrusion as well as blow molding, injection molding and rotary molding. Films include blown or cast films formed by coextrusion or by lamination useful as shrink film, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, membranes, etc. in food-contact and non-food contact applications. Fibers include melt spinning, solution spinning and melt blown fiber operations for use in woven or non-woven form to make filters, diaper fabrics, medical garments, geotextiles, etc. Extruded articles include medical tubing, wire and cable coatings, geomembranes, and pond liners. Molded articles include single and multi-layered constructions in the form of bottles, tanks, large hollow articles, rigid food containers and toys, etc.